Temperatures are higher, snow is melting sooner and more extensively, and sea and land ice are diminishing. Those are some of the findings in this year's Arctic Report Card, recently released by the National Oceanic and Atmospheric Administration.
The report card is a comprehensive summary of observed conditions in the global northern ecosystem that's released annually.
While the report outlines a number of changes and changing trends, it lists retreating sea ice as the "most pervasive threat to ice-associated marine mammals, including walruses."
According to data, the minimum sea ice extent observed this past September was 29 percent less than the averages measured between 1981 and 2010. It was also the fourth lowest recorded since satellite measurements began in 1979.
The lowest maximum sea ice extent ever recorded also occurred this spring — 7 percent less than the average since 1981. Not only did the ice retreat faster and earlier than usual, it was of a different makeup from how it typically has been over the past 30 years.
In 1985, ice older than 4 years made up 20 percent of the pack ice and 35 percent was first-year ice. In February and March of this year, old ice made up only 3 percent compared to 70 percent new.
All of these figures contribute to an uncertain future for marine mammals that depend on sea ice.
Walruses in the Arctic have been observed traveling long distances to haul out on land rather than on nearby sea ice as they would have in the past. That's in part due to the fact that there's simply less ice and, consequently, the ice has a lower carrying capacity for walruses than it used to.
Diminishing ice has serious consequences for other facets of the ecosystem too. With less protective ice cover in the sunny summer months, sea surface temperatures have risen in recent years, with the Chukchi Sea demonstrating one of the most pronounced warming trends — a steady increase of half a degree centigrade per decade — since 1982. Arctic snow cover, or the amount of snow on the ground during certain parts of the year, has also been declining. Snow has been melting earlier in the year over the past decade, leading to longer, browner summer months. Snow cover this June was the second lowest on record since 1979; there's been an 18 percent decline in June snow cover per decade measured since then as well.
Another indicator in the report, aside from marine mammals, is the annual discharge of Arctic rivers, meaning the release of fresh water into surrounding environments that can drastically change the biology, chemistry and circulation of coastal and ocean ecosystems. There has been much more significant discharge over the past two years than in years past.
With regard to air temperature, over the past year, temperatures have consistently been recorded at more than 2 degrees Fahrenheit above average since the start of the 20th century.
The amount of vegetation on land is also shifting and certain parts of the state, including the Yukon-Kuskokwim Delta, have experienced surface "browning" in recent years, which can have consequences for land mammals and birds.
While the precise implications of these observed changes isn't known yet, what is known is that the Arctic ecosystem is not what it used to be.
To read the entire 2015 Arctic Report Card, visit arctic.noaa.gov.